To golf it a little to make it into an actual one-liner (even if a
rather long one!)
#!/usr/bin/perl -l
$n=pop;$"=$/;print"@{[w($n)]}";sub
w{my($n)=pop;[EMAIL PROTECTED]"":[EMAIL
PROTECTED]"()":a;if($n>1){for$k(0..--$n){for$p(w($k))[EMAIL
PROTECTED],"($p)$_"for
w($n-$k)[EMAIL PROTECTED]
-- jas
On Nov 15, 2007 2:05 PM, Phil Carmody <[EMAIL PROTECTED]> wrote:
> I saw this on sci.math, and thought "one liner" ;-)
> I even think a DP non-recursive approach should be quite quick.
> Keeping the output in the logical order might cost a few strokes.
>
>
> #!/usr/bin/perl
>
> $count = $ARGV[0];
>
> print join "\n", pren($count), "";
>
> sub pren
> {
> my @list = ();
>
> (my $n) = @_;
> if ($n == 0) {push(@list, "")}
> elsif($n == 1) {push(@list, "()")}
> elsif($n > 1)
> {
> foreach $k (0 .. $n-1)
> {
> foreach $p1 (pren($k))
> {
> foreach $p2 (pren($n - 1 - $k))
> {
> push @list, sprintf "(%s)%s", $p1, $p2;
> }
> }
> }
> }
> return @list;
> }
> ________________________
>
>
> $ ./parens.pl 5 | cat -n
> 1 ()()()()()
> 2 ()()()(())
> 3 ()()(())()
> 4 ()()(()())
> 5 ()()((()))
> 6 ()(())()()
> 7 ()(())(())
> 8 ()(()())()
> 9 ()((()))()
> 10 ()(()()())
> 11 ()(()(()))
> 12 ()((())())
> 13 ()((()()))
> 14 ()(((())))
> 15 (())()()()
> 16 (())()(())
> 17 (())(())()
> 18 (())(()())
> 19 (())((()))
> 20 (()())()()
> 21 (()())(())
> 22 ((()))()()
> 23 ((()))(())
> 24 (()()())()
> 25 (()(()))()
> 26 ((())())()
> 27 ((()()))()
> 28 (((())))()
> 29 (()()()())
> 30 (()()(()))
> 31 (()(())())
> 32 (()(()()))
> 33 (()((())))
> 34 ((())()())
> 35 ((())(()))
> 36 ((()())())
> 37 (((()))())
> 38 ((()()()))
> 39 ((()(())))
> 40 (((())()))
> 41 (((()())))
> 42 ((((()))))
>
>
> () ASCII ribbon campaign () Hopeless ribbon campaign
> /\ against HTML mail /\ against gratuitous bloodshed
>
> [stolen with permission from Daniel B. Cristofani]
>
>
>
> ____________________________________________________________________________________
> Never miss a thing. Make Yahoo your home page.
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>
--
Jasvir Nagra
http://www.cs.auckland.ac.nz/~jas
